U.S. patent number 5,428,665 [Application Number 08/141,094] was granted by the patent office on 1995-06-27 for method of managing supplementary service procedures in gsm/vlr towards hlr.
This patent grant is currently assigned to Telefonaktiebolaget LM Ericsson. Invention is credited to Sven J. Lantto.
United States Patent |
5,428,665 |
Lantto |
June 27, 1995 |
Method of managing supplementary service procedures in GSM/VLR
towards HLR
Abstract
In a Mobile Services Switching Center/Visitor Location Register
(MSC/VLR), requests (made by a mobile station (MS)) for
supplementary services may require processing only by the MSC/VLR,
or they may require processing by a Home Location Register (HLR). A
method of managing supplementary service procedures that are
processed by an HLR includes supplying the MSC/VLR with a list
containing only those supplementary service operations that shall
be terminated in the MSC/VLR. In the MSC/VLR, a forward direction
message is received from an MS, the forward direction message
including an intended supplementary service operation. Then, the
intended supplementary service operation is compared with the list
of supplementary service operations. If the intended supplementary
service operation is contained in the list of supplementary service
operations, then the intended operation is terminated in the
MSC/VLR. However, if the intended supplementary service operation
is not contained in the list of supplementary service operations,
then the forward direction message is forwarded, unaltered, to the
HLR.
Inventors: |
Lantto; Sven J. (Tullinge,
SE) |
Assignee: |
Telefonaktiebolaget LM Ericsson
(Stockholm, SE)
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Family
ID: |
20387577 |
Appl.
No.: |
08/141,094 |
Filed: |
October 26, 1993 |
Foreign Application Priority Data
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Oct 27, 1992 [SE] |
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9203144 |
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Current U.S.
Class: |
455/414.1;
455/433; 380/248 |
Current CPC
Class: |
H04W
4/10 (20130101); H04W 76/45 (20180201) |
Current International
Class: |
H04Q
7/24 (20060101); H04Q 7/38 (20060101); H04Q
007/22 () |
Field of
Search: |
;379/58,59
;380/21,23,43,48 ;455/33.1 ;340/825.31,825.34 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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295678 |
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Dec 1988 |
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EP |
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462728 |
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Dec 1991 |
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EP |
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Other References
Ballard, Issermann, Sanchez, "Cellular Mobile Radio as an
Intelligent Network Application", Electrical Communication 1989.
.
Delory, Treillard, "Security and Saturation Solutions for GSM"
Telephone Engineer and Mangement, Jan. 16, 1991..
|
Primary Examiner: Kuntz; Curtis
Assistant Examiner: Cumming; William
Attorney, Agent or Firm: Burns, Doane, Swecker &
Mathis
Claims
What is claimed is:
1. In Switching Center/Visitor Location Register (MSC/VLR), a
method of managing supplementary service procedures that are
processed by a Home Location Register (HLR), comprising the steps
of:
a) supplying the MSC/VLR with a list comprising only those
supplementary service operations that shall be terminated in the
MSC/VLR;
b) in the MSC/VLR, receiving a forward direction message from a
Mobile Station (MS), the forward direction message including an
intended supplementary service operation, and then comparing the
intended supplementary service operation with the list of
supplementary service operations;
c) if the intended supplementary service operation is contained in
the list of supplementary service operations, then terminating the
intended supplementary service operation in the MSC/VLR; and
d) if the intended supplementary service operation is not contained
in the list of supplementary service operations, then forwarding
the forward direction message unaltered to the HLR,
wherein:
the forward direction message is an invoke component;
the intended supplementary service operation is encoded in an
intended Operation Code contained in the invoke component;
the list of supplementary service operations is a list of Operation
Codes corresponding to only those supplementary service operations
that shall be terminated in the MSC/VLR;
in step b), comparing the intended supplementary service operation
with the list of supplementary service operations comprises
comparing the intended Operation Code with the list of Operation
Codes;
step c) comprises terminating the intended supplementary service
operation in the MSC/VLR if the intended Operation Code coincides
with one of the Operation Codes contained in the list of Operation
Codes; and
step d) comprises forwarding the forward direction message
unaltered to the HLR if the intended Operation Code does not
coincide with any one of the Operation Codes contained in the list
of Operation Codes.
Description
BACKGROUND
The present invention generally relates to cellular mobile radio
systems based upon the so called GSM standard (GSM--Global System
for Mobile communication) and more particularly to a method of
managing supplementary service procedures.
A GSM network basically comprises at least one base station system
BSS including a base station controller BSC and base station
transceivers BTS. The GSM network furthermore includes a mobile
services switching centre MSC, a home location register HLR and a
visitors location register VLR.
Each subscribing mobile station MS belongs to a HLR in a home
network, wherein permanent subscriber data is stored. When a mobile
station is registered in a MSC/VLR as a new visitor, that mobile
station's HLR sends a copy of the relevant subscriber data to
MSC/VLR.
Supplementary service procedures are those procedures that are used
by an MS (Mobile Station) in the GSM-system either to change
supplementary service data or to question the network about current
supplementary service data. This procedure may, for instance,
involve activating a supplementary service, registering data for a
supplementary service, inquiring about data for a given
supplementary service, etc.
In a GSM-network, subscriber data is stored permanently in HLR as
indicated above. This implies that procedures used by an MS to
request changes in subscriber service data will preferably be
terminated in HLR, which is responsible for such data. The MSC/VLR
responsible for signalling with MS store only copies of the
supplementary service data. This data is received in MSC/VLR from
HLR in conjunction with a report from MS that the mobile is a new
"visitor" in MSC/VLR.
Since it is MSC/VLR that communicates directly with MS in
conjunction with supplementary service procedures, it is MSC/VLR
that terminates these procedures as seen from MSC. However, as
mentioned, the GSM-network is distributed so that, in the main, it
is the HLR which is the actual recipient or target of these
procedures. MSC/VLR merely constitutes a procedure transfer point.
This is an exception rather than a rule however, since certain
procedures are terminated in MSC/VLR and not all of the procedures
are transferred to HLR. An example in this respect is found in a
query which concerns data that is applicable at that time for a
given supplementary service, this query being terminated in MSC/VLR
and not in HLR. This applies, however, only to those services that
are controlled by MSC/VLR. When signalling between MS and MSC/VLR,
the supplementary service procedures are implemented purely in
protocol fashion with the aid of rules that are in accord with the
ROSE-concept (Remote Operations Service Element--specified in CCITT
X.219 and X.220). This means that all procedures are specified in a
protocol fashion as operations. These operations are descriptions
of the configuration of the forward and backward messages included
in the actual procedure from the aspect of their protocol content.
The forward and backward messages included in an operation are
called components.
CCITT #7 TCAP (Translation Capabilities Application Part--specified
in CCITT Q.771-Q.775) is utilized when signalling between MSC/VLR
and HLR. TCAP is also based on ROSE. This enables operations that
are used in signalling between MSC/VLR and MS to be "imported" and
used also when signalling between MSC/VLR and HLR.
EP 295,678 describes a radio telephony system in which a "radio
connector" sends an ID-number for the radio zone in which it is
located. The radio telephone compares the received radio-zone
ID-number with the number stored in a memory. If the ID-numbers do
not mutually coincide, the radio-telephone ID-number and the
received radio-zone ID-number are sent as a position entry signal
to a radio control unit, via a "radio connector". The radio-channel
control unit registers the two ID-numbers.
U.S. Pat. No. 4,901,340 discloses essentially a general picture of
the standpoint of techniques with regard to mobile telephony, where
mobiles are located in foreign areas outside their home service
area.
SUMMARY
As will be evident from the above, when MSC/VLR receives a
supplementary service operation from a mobile station it is
necessary for MSC/VLR to decide whether the operation shall be
terminated in MSC/VLR or forwarded to HLR. The object of the
present invention is to simplify the procedure when the operation
concerned shall not be terminated in MSC/VLR, but shall be
forwarded to HLR.
This object is achieved in a method of managing supplementary
service procedures in GSM/VLR towards HLR which, in accordance with
the invention, comprises the following steps
a) letting MSC/VLR be aware only of those operations that shall be
terminated in MSC/VLR,
b) checking the intended operation when receiving a forward
direction message within an operation from an MS for deciding
whether the operation is known to MSC/VLR, and
c) if the operation is known to MSC/VLR, terminating it in
MSC/VLR,
d) if the operation is not known to MSC/VLR, making no further
check of it but forwarding the message to HLR in the condition in
which it was received in MSC/VLR.
A preferred embodiment comprises the following steps checking in
step b) the invoke component of said operation by the Operation
Code,
terminating in step c) the operation if the value the of Operation
Code coincides with a value known to MSC/VLR,
making in step d) no further check of the received invoke component
if the value of Operation Code is not known to MSC/VLR but
forwarding it to HLR in the condition in which it was received in
MSC/VLR.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with reference
to the accompanying drawings, in which
FIG. 1 is a schematic diagram illustrating the basic structure of a
conventional GSM network,
FIG. 2 illustrates schematically a conventional supplementary
service procedure including signalling between MS and MSC/VLR and
between MSC/VLR and HLR, and
FIG. 3 illustrates similarly an example of how MSC/VLR manages a
supplementary service procedure from MS which shall be forwarded to
HLR, in accordance with the present invention.
DETAILED DESCRIPTION
With reference to FIG. 1, a GSM cellular network basically
comprises a number of base station systems, of which two are
generally indicated at BSS1 and BSS2, respectively. Each of the
base station systems BSS1 and BSS2 includes a base station
controller BSC1 and BSC2, respectively, connected to base station
transceivers BTS via communication links L, one of said base
station transceivers being designated BTS.sub.N in FIG. 1. Each
transceiver BTS is located in an associated cell of the cellular
network, which is shown in FIG. 1 as a honeycomb structure wherein
each hexagon represents a cell. In FIG. 1 the cell containing the
transceiver BTS.sub.N is designated C.sub.N. The GSM network
furthermore includes a mobile services switching centre MSC having
a visitors location register VLR. There are furthermore one or more
home location registers communicating with MSC. The MSC is
connected for communication with the base station controllers BSC1
and BSC2 via a public land mobile network PLMN.
Although not shown, the MSC shown in FIG. 1 usually has an
interface to other MSCs, each MSC having furthermore interfaces for
connection to a local public switched telephone network.
Each subscribing mobile station MS belongs to a HLR in a home
network, wherein permanent subscriber data is stored. When a mobile
is registered in a MSC/VLR as a new visitor, HLR sends a copy of
the relevant subscriber data to MSC/VLR.
When signalling between MS and MSC/VLR, the supplementary service
procedures are implemented purely in protocol fashion with the aid
of rules that are in accord with the ROSE-concept (Remote
Operations Service Element--specified in CCITT X.219 and X.220).
This means that all procedures are specified in a protocol fashion
as operations. These operations are descriptions of the
configuration of the forward and backward messages included in the
actual procedure from the aspect of their protocol content. The
forward and backward messages included in an operation are called
components.
CCITT #7 TCAP (Translation Capabilities Application Part--specified
in CCITT Q.771-Q.775) is utilized when signalling between MSC/VLR.
TCAP is also based on ROSE. This enables operations that are used
in signalling between MSC/VLR and MS to be "imported" and used also
when signalling between MSC/VLR and HLR. CCITT X.219, X.220, and
Q.771-Q.775 are incorporated here by reference.
FIG. 2 illustrates an example of conventional supplementary service
procedures, including signalling between MS and MSC/VLR and also
between MSC/VLR and HLR.
When signalling between MS, indicated in FIG. 2 as a block 2, and
MSC/VLR, similarily indicated as a block 4, the procedure is
started by MS, by signalling the forward message in the operation
(called invoke component) "ActivateSS" in a REGISTER-message 6. The
REGISTER-message thus establishes a signalling connection between
MS and MSC/VLR. A dialogue is established by MSC/VLR 4 by sending a
TCAP TC-BEGIN message 8 containing the invoke component of the
operation "ActivateSS" to HLR, indicated as a block 10.
A TCAP TC-CONTINUE message 12 containing the invoke component of
the operation "GetPassword" is used by HLR to continue signalling
in this dialogue. In response, MSC/VLR forwards a FACILITY-message
14 containing the invoke component of the operation "GetPassword"
to MS. MS answers in a FACILITY-message 16 containing the return
result component of the operation "GetPassword" to MSC. MSC
continues by forwarding the TCAP TC-CONTINUE message 18 containing
the return result component of the operation "GetPassword" to
HLR.
Generally, in response to a message from MS, MSC/VLR can either
send a FACILITY-message, such as 14, or a RELEASE COMPLETE-message,
such as 20. The FACILITY-message is used to signal on an existing
signalling connection without releasing the connection. The RELEASE
COMPLETE-message is used to release the signal connection.
The FACILITY-message and the RELEASE COMPLETE-message are used
either to respond to the requested operation either with a positive
or with a negative reply, and to start a new operation when so
required.
Generally, between MSC and HLR, a dialogue is established by
sending a TC-BEGIN message. TC-CONTINUE is used to continue
signalling in this dialogue, and TC-END 22 is used to end the
dialogue. The user is able to send different types of components in
all of these TCAP-messages.
As appears from the above, MSC/VLR when receiving a supplementary
operation must decide whether it shall be terminated in MSC/VLR or
if it shall be passed on to HLR. The present invention relates to
the case where the procedure shall not be terminated in MSC/VLR but
shall be passed on to HLR.
The invention implies that MSC/VLR is aware solely of those
operations that shall be terminated in MSC/VLR. When receiving an
invoke component within an operation from an MS, a check is made to
determine the operation concerned. This is indicated by a value
called an Operation Code. With reference to FIG. 3, MSC/VLR in step
30 analyses the Operation Code. If the Operation Code value
coincides, as decided in step 32, with one of the values known to
MSC/VLR, the procedure is terminated in MSC/VLR, step 34.
If the operation code value is not known to MSC/VLR, MSC/VLR makes
no further syntactic check of the received invoke component.
When practicing conventional standards for signalling between
MSC/VLR and HLR, it would now have been normal practice to create a
new invoke component of which a part includes new data allocated by
MSC/VLR and also data that MSC/VLR has received from MS. This has
meant that MSC/VLR must be aware of some part of the content of
operations that are actually transparent to MSC/VLR, and also the
identity of these operations and how they function.
Instead of MSC/VLR being aware of those operations that shall be
signalled or forwarded to HLR, the invention is based on the
concept that MSC/VLR will be aware solely of those operations that
shall not be signalled to HLR. In accordance with this solution,
those operations that shall not be terminated in MSC/VLR, i.e.
operations that shall be signalled to HLR, are unknown to MSC/VLR
and shall be one-hundred percent transparent to MSC/VLR.
Instead of allocating certain own data within the invoke component,
the component in step 36 is forwarded to HLR in the TCAP-message
TC-BEGIN totally in the condition in which it was received from MS,
i.e. without MSC/VLR being aware of the operation concerned or of
other data.
MSC/VLR has now "opened a signalling channel" on which HLR and MS
can exchange components included in any desired number of
operations, without MSC/VLR needing to know to which operations
signalling between MS and HLR via MSC/VLR relates, or the contents
of these operations.
In turn, this means that new operations and changes in existing
operations, such as new data or new negative acknowledgements for
instance (according to TCAP, so-called ERRORS) can be introduced
into HLR and in MS without influencing MSC/VLR. This provides good
properties with regard to the introduction of new services in HLR
without influencing MSC/VLR. This is particularly beneficial in
GSM, where the HLR operator is sometimes not the same as the
MSC/VLR operator (MS is located in another network, for instance in
another country).
* * * * *